1. Field of the Invention
The present invention relates to a medical treatment instrument.
2. Description of Related Art
In the related art, medical treatment tools for performing various kinds of treatment on a living body tissue have been studied.
For example, a high-frequency knife described in Japanese Patent No. 3923022 includes a sheath, and an operation unit provided at a base end of the sheath. A tubular stopper member is coupled to a tip of the sheath. A conductive operating wire (operating member) is inserted through the inside of the sheath so as to be movable in an axis direction. A distal end portion of the operating wire is mounted with a stopper receiving portion that abuts against the aforementioned stopper member. A knife unit (treatment unit) is connected to the stopper receiving portion. A tip of the knife unit is formed with a bent portion that is substantially bent at a right angle.
The operation unit includes a substantially shaft-shaped operation unit body (body portion), and an operating slider (sliding portion) that is slidable in an axis direction with respect to the operation unit body. A rotor provided at a base end of the sheath is rotatably connected to the operation unit body.
The operating wire can be advanced and retracted in the axis direction in an inner hole of the sheath by the sliding operation of the operating slider in the axis direction, and the knife unit can be protruded and retracted from the distal end portion of the sheath by the advance/retraction operation of the operating wire. The rotation of the knife unit can be suppressed by the contact pressure generated when the stopper receiving portion contacts to the stopper member.
When it is desired to change the orientation of the bent portion around the axis during treatment, the operating slider is slightly moved rearward (pulled back) with respect to the operation unit body, and the stopper receiving portion is separated from the stopper member. If the sheath is gripped and the operation unit is rotated around the axis, the knife unit rotates simultaneously around the axis, and the orientation of the bent portion changes. When the bent portion has the desired orientation, the operating slider is moved forward (pushed) with respect to the operation unit body, and the stopper receiving portion is pressed against the stopper member. At this time, even if an external force is applied to the knife unit, the orientation of the bent portion is not changed by the aforementioned contact pressure.
However, in the high-frequency knife, a state where the stopper receiving portion is pressed against the stopper member, that is, the operating slider is pushed, should be maintained in order for the orientation of the knife unit not to change.
A high-frequency knife is described also in the specification of United States Patent Application, Publication No. 2008-0306334. The high-frequency knife described in the specification of United States Patent Application, Publication No. 2008-0306334 is different from the high-frequency knife described in the aforementioned Japanese Patent No. 3923022 in that a linear member inserted through the sheath has a structure in which an energizing wire is inserted into a coiled sheath, and a ratchet mechanism is provided.
The coiled sheath is a member having higher rigidity when being compressed.
The aforementioned ratchet mechanism is provided at the operation unit, and limits pull-back of the operating slider. The ratchet mechanism has a plurality of teeth provided at the operation unit body closer to a tip side than the operating slider, and a claw pivoted at the tip of the operating slider by a pin and biased by a spring in a direction in which the claw meshes with the teeth. When the ratchet mechanism is released to pull back the operating slider, the engagement between the claw and the teeth is released by pushing a button at a base end of the claw so as to be brought close to the axis of the sheath.
In the high-frequency knife configured in this way, if the operating slider is pushed with respect to the operation unit body, the linear member is compressed and the coiled sheath becomes rigid. Since the ratchet mechanism is provided, it is not necessary to continue holding the operating slider in order to maintain the compressed state of the linear member, and the operating slider can be released from the hand. When the knife unit is made to protrude from the tip of the sheath, is moved, and performs incision, the coiled sheath becomes rigid, deflection can be prevented, and a sufficient amount of incision with respect to a traveling distance can be performed.